This application requests bloc travel support for citizens of the United States participating in the 4th International Congress on Inborn Errors of Metabolism to be held in Sendai, Japan, from May 27-30, 1987. Based on responses received in Japan to a preliminary announcement, as of July, 1985, 168 U.S. scientists have declared their desire to participate. A preliminary call for abstracts to SIMD members in October, 1985, resulted in thirty received within one month. From these initial inquiries, there is clear U.S. interest in exchanging information at this international congress. This congress comes at a critical time when the historical significances of rare "inborn errors of metabolism" are extending to the exciting biological resolution offered by new molecular techniques. The potential is great for understanding both normal and pathological phenomena in humans produced by variations in gene structure, expression, mRNA processing, and post-translational regulation in the control of human metabolic processes. These unique experiments of nature are caused by single mutant genes of large effect with defined biochemical phenotypes. They offer insight into the relationships between altered DNA, altered protein structure, and pathophysiological processes. They are individually rare and of varying frequency and expression in different ethnic populations. Thus it is imperative that collective experiences be shared at frequent intervals on an international basis. Although three previous congresses have met, only one (1980, Interlaken, Switzerland) had significant U.S. participation due to U.S. restrictions on grant funds for foreign travel. Attendance and participation at this congress by U.S. scientists must be as large as possible that we may continue to contribute to the quality of scientific exchange and thereby enhance research and education concerning inherited metabolic disorders throughout the world.